package com.example.multiple.config.datasource;

import org.apache.ibatis.exceptions.PersistenceException;
import org.apache.ibatis.executor.BatchResult;
import org.apache.ibatis.session.*;
import org.mybatis.spring.MyBatisExceptionTranslator;
import org.mybatis.spring.SqlSessionTemplate;
import org.springframework.dao.support.PersistenceExceptionTranslator;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.util.List;
import java.util.Map;

import static java.lang.reflect.Proxy.newProxyInstance;
import static org.apache.ibatis.reflection.ExceptionUtil.unwrapThrowable;
import static org.mybatis.spring.SqlSessionUtils.*;


/**
 * 自定义SqlSessionTemplate，动态切换数据源
 */
public class DynamicSqlSessionTemplate extends SqlSessionTemplate
{
    private final SqlSessionFactory sqlSessionFactory;
    private final ExecutorType executorType;
    private final SqlSession sqlSessionProxy;
    private final PersistenceExceptionTranslator exceptionTranslator;
    private Map<Object, SqlSessionFactory> targetSqlSessionFactorys;
    private SqlSessionFactory defaultTargetSqlSessionFactory;

    public DynamicSqlSessionTemplate(SqlSessionFactory sqlSessionFactory)
    {
        this(sqlSessionFactory, sqlSessionFactory.getConfiguration().getDefaultExecutorType());
    }

    public DynamicSqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType)
    {
        this(sqlSessionFactory, executorType, new MyBatisExceptionTranslator(
                sqlSessionFactory.getConfiguration().getEnvironment().getDataSource(), true));
    }

    public DynamicSqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType,
                                     PersistenceExceptionTranslator exceptionTranslator)
    {
        super(sqlSessionFactory, executorType, exceptionTranslator);
        this.sqlSessionFactory = sqlSessionFactory;
        this.executorType = executorType;
        this.exceptionTranslator = exceptionTranslator;
        this.sqlSessionProxy = (SqlSession) newProxyInstance(SqlSessionFactory.class.getClassLoader(),
                new Class[] { SqlSession.class }, new SqlSessionInterceptor());
        this.defaultTargetSqlSessionFactory = sqlSessionFactory;
    }

    public void setTargetSqlSessionFactorys(Map<Object, SqlSessionFactory> targetSqlSessionFactorys)
    {
        this.targetSqlSessionFactorys = targetSqlSessionFactorys;
    }

    public void setDefaultTargetSqlSessionFactory(SqlSessionFactory defaultTargetSqlSessionFactory)
    {
        this.defaultTargetSqlSessionFactory = defaultTargetSqlSessionFactory;
    }

    @Override
    public SqlSessionFactory getSqlSessionFactory()
    {
        SqlSessionFactory targetSqlSessionFactory = targetSqlSessionFactorys
                .get(DynamicDataSourceContextHolder.getDataSourceType());
        if (targetSqlSessionFactory != null)
        {
            return targetSqlSessionFactory;
        }
        else if (defaultTargetSqlSessionFactory != null)
        {
            return defaultTargetSqlSessionFactory;
        }
        return this.sqlSessionFactory;
    }

    @Override
    public Configuration getConfiguration()
    {
        return this.getSqlSessionFactory().getConfiguration();
    }

    public ExecutorType getExecutorType()
    {
        return this.executorType;
    }

    public PersistenceExceptionTranslator getPersistenceExceptionTranslator()
    {
        return this.exceptionTranslator;
    }

    /**
     * {@inheritDoc}
     */
    public <T> T selectOne(String statement)
    {
        return this.sqlSessionProxy.<T> selectOne(statement);
    }

    /**
     * {@inheritDoc}
     */
    public <T> T selectOne(String statement, Object parameter)
    {
        return this.sqlSessionProxy.<T> selectOne(statement, parameter);
    }

    /**
     * {@inheritDoc}
     */
    public <K, V> Map<K, V> selectMap(String statement, String mapKey)
    {
        return this.sqlSessionProxy.<K, V> selectMap(statement, mapKey);
    }

    /**
     * {@inheritDoc}
     */
    public <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey)
    {
        return this.sqlSessionProxy.<K, V> selectMap(statement, parameter, mapKey);
    }

    /**
     * {@inheritDoc}
     */
    public <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey, RowBounds rowBounds)
    {
        return this.sqlSessionProxy.<K, V> selectMap(statement, parameter, mapKey, rowBounds);
    }

    /**
     * {@inheritDoc}
     */
    public <E> List<E> selectList(String statement)
    {
        return this.sqlSessionProxy.<E> selectList(statement);
    }

    /**
     * {@inheritDoc}
     */
    public <E> List<E> selectList(String statement, Object parameter)
    {
        return this.sqlSessionProxy.<E> selectList(statement, parameter);
    }

    /**
     * {@inheritDoc}
     */
    public <E> List<E> selectList(String statement, Object parameter, RowBounds rowBounds)
    {
        return this.sqlSessionProxy.<E> selectList(statement, parameter, rowBounds);
    }

    /**
     * {@inheritDoc}
     */
    @SuppressWarnings("rawtypes")
    public void select(String statement, ResultHandler handler)
    {
        this.sqlSessionProxy.select(statement, handler);
    }

    /**
     * {@inheritDoc}
     */
    @SuppressWarnings("rawtypes")
    public void select(String statement, Object parameter, ResultHandler handler)
    {
        this.sqlSessionProxy.select(statement, parameter, handler);
    }

    /**
     * {@inheritDoc}
     */
    @SuppressWarnings("rawtypes")
    public void select(String statement, Object parameter, RowBounds rowBounds, ResultHandler handler)
    {
        this.sqlSessionProxy.select(statement, parameter, rowBounds, handler);
    }

    /**
     * {@inheritDoc}
     */
    public int insert(String statement)
    {
        return this.sqlSessionProxy.insert(statement);
    }

    /**
     * {@inheritDoc}
     */
    public int insert(String statement, Object parameter)
    {
        return this.sqlSessionProxy.insert(statement, parameter);
    }

    /**
     * {@inheritDoc}
     */
    public int update(String statement)
    {
        return this.sqlSessionProxy.update(statement);
    }

    /**
     * {@inheritDoc}
     */
    public int update(String statement, Object parameter)
    {
        return this.sqlSessionProxy.update(statement, parameter);
    }

    /**
     * {@inheritDoc}
     */
    public int delete(String statement)
    {
        return this.sqlSessionProxy.delete(statement);
    }

    /**
     * {@inheritDoc}
     */
    public int delete(String statement, Object parameter)
    {
        return this.sqlSessionProxy.delete(statement, parameter);
    }

    /**
     * {@inheritDoc}
     */
    public <T> T getMapper(Class<T> type)
    {
        return getConfiguration().getMapper(type, this);
    }

    /**
     * {@inheritDoc}
     */
    public void commit()
    {
        throw new UnsupportedOperationException("Manual commit is not allowed over a Spring managed SqlSession");
    }

    /**
     * {@inheritDoc}
     */
    public void commit(boolean force)
    {
        throw new UnsupportedOperationException("Manual commit is not allowed over a Spring managed SqlSession");
    }

    /**
     * {@inheritDoc}
     */
    public void rollback()
    {
        throw new UnsupportedOperationException("Manual rollback is not allowed over a Spring managed SqlSession");
    }

    /**
     * {@inheritDoc}
     */
    public void rollback(boolean force)
    {
        throw new UnsupportedOperationException("Manual rollback is not allowed over a Spring managed SqlSession");
    }

    /**
     * {@inheritDoc}
     */
    public void close()
    {
        throw new UnsupportedOperationException("Manual close is not allowed over a Spring managed SqlSession");
    }

    /**
     * {@inheritDoc}
     */
    public void clearCache()
    {
        this.sqlSessionProxy.clearCache();
    }

    /**
     * {@inheritDoc}
     */
    public Connection getConnection()
    {
        return this.sqlSessionProxy.getConnection();
    }

    /**
     * {@inheritDoc}
     *
     * @since 1.0.2
     */
    public List<BatchResult> flushStatements()
    {
        return this.sqlSessionProxy.flushStatements();
    }

    /**
     * Proxy needed to route MyBatis method calls to the proper SqlSession got from Spring's Transaction Manager It also
     * unwraps exceptions thrown by {@code Method#invoke(Object, Object...)} to pass a {@code PersistenceException} to
     * the {@code PersistenceExceptionTranslator}.
     */
    private class SqlSessionInterceptor implements InvocationHandler
    {
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable
        {
            final SqlSession sqlSession = getSqlSession(DynamicSqlSessionTemplate.this.getSqlSessionFactory(),
                    DynamicSqlSessionTemplate.this.executorType, DynamicSqlSessionTemplate.this.exceptionTranslator);
            try
            {
                Object result = method.invoke(sqlSession, args);
                if (!isSqlSessionTransactional(sqlSession, DynamicSqlSessionTemplate.this.getSqlSessionFactory()))
                {
                    sqlSession.commit(true);
                }
                return result;
            }
            catch (Throwable t)
            {
                Throwable unwrapped = unwrapThrowable(t);
                if (DynamicSqlSessionTemplate.this.exceptionTranslator != null
                        && unwrapped instanceof PersistenceException)
                {
                    Throwable translated = DynamicSqlSessionTemplate.this.exceptionTranslator
                            .translateExceptionIfPossible((PersistenceException) unwrapped);
                    if (translated != null)
                    {
                        unwrapped = translated;
                    }
                }
                throw unwrapped;
            }
            finally
            {
                closeSqlSession(sqlSession, DynamicSqlSessionTemplate.this.getSqlSessionFactory());
            }
        }
    }
}
